
[1]}.
Note that by the Wiener-Khinchin theorem the autocovariance function \(r\)  and the spectral measure \(\zeta \)  of \(G\)  are directly related by the Fourier transform, i.e. \(r(t)=\int _{\mathbb {R}}e^{it\omega }\zeta (d\omega )\) , and one can compute
\(\zeta (d\omega )=\sum _{k=1}^\infty \frac{\Gamma _j^{-2/\alpha }}{2}\left(\delta \left(d\omega - Z_j\right)+\delta \left(d\omega + Z_j\right)\right)\) 
